1. Field of the Invention
The present invention relates to a water pump for a water-cooled engine.
2. Description of Related Art
Japanese Utility Model Publication No. Hei 6-31197 discloses a structure of a water pump for a water-cooled engine of a motorcycle. In the water pump, an impeller is attached to one end of a hollow pump shaft, and a pump gear is attached to the other end of the pump shaft. The pump gear rotates in response to rotation of a crankshaft. The pump shaft is supported by a crankcase of the crankshaft.
The pump gear receives a thrust load from a pin. The pin has its opposite ends supported in the crankcase via the pump gear and is orthogonal to the crankcase. The pump gear is surface-supported by the crankcase.
In order to receive the thrust load by the pin, as described above, a drilling process and a force-fitting process are required in order to install the pin. Therefore, the number of components, including the pin itself, is increased. Further, the manufacturing and repair process is difficult. In order to support the pump shaft at the opposite ends thereof, the pump shaft should be centered very precisely. Therefore, the pump shaft is preferably supported at one end thereof